Sound attenuating gas pipe



Sept. 24, 1963 E.1 UDL.ow ETAL souNn ATTENUATING GAS PIPE Filed Deo. l2, 1960 INVENTORS. foMuNn LuoLow AND BYB--A/J'Anfmv H. IRWIN AT1-o2 NE vs.

United States Patent O aromas SOUND ATTENUATING GAS PIPE Edmund Ludlow and Benjamin H. Irwin, Columbus, Ind., assignors to Arvin Industries, Inc., Columbus, Ind., a corporation of Indiana Filed Dec. 12, 1960, Ser. No. 75,291 Claims. (Si. itil- 59) This invention relates to Ia sound attenuating gas pipe, and more particularly to a sound attenuating gas pipe for use in association with internal com-bustion engines for conveying the exhaust gases therefrom and for attenuating the noise level of said exhaust gases.

It is an object of our invention to provide a sound attenuating pipe which will convey the exhaust gases emanating from an internal combustion engine, which will attenuate the noise level of such exhaust gases, which will effect such sound attenuation over a wide range of frequencies, which can be economically manufactured from metal-tubing and sheet-metalvstampings, and which will have limited space requirements.

In accordance with the preferred form of our invention, there is provided an elongated pipe having an elongated wall surface mounted within it and partitioning the pipe interior Iinto a main Vgas-flow passage and la plurality of'axially spaced resonator volumes, the end walls of said resonator volumes being formed by a plurality of projections formed in said Wal-l surface and |abutting the pipe inner Wall. A plurality of channeled members are mounted on said wall surfaces and act in combination therewith to form a plurality of resonator volume throats opening into the resonator volumes and the main gasfiow passage to operatively interconnect said volumes and passage `for silencing the 'gases movi-ng through said passage.

Other objects and features of our invention will become lapparent :from the more detailed description which follows and from the accompanying drawings, in which:

FIG. l is an isometric view partially in section showing a gas pipe embodying our invention;

FIG. 2 is an enlarged fragmentary longitudinal section of the gas pipe shown inFIG. 1;

FIG. 3 is an enlarged vertical section taken on'the line 3 3` of FIG. 2;

FIG. 4 is a vertical section si-milar to FIG. 3 but showing a modified form of our invention; and

FIG. 5 is a fragmentary isometric view of the stamping shown in FIG. 2.

Our sound attenuating gas pipe is adapted to convey the exhaust 'gases away from an internal combustion engine and to reduce -the noise level of said gases. As shown in the drawing, our invention comprises an elongated pipe adapted to be connected 'to the exhaust manifold of an internal com-bustion engine by a conventional mounting ange 12. Conveniently, the pipe 10 may have an outer diameter of about 2.25 inches, the diameter of conventional exhaustand tail pipes.

Mounted on the interior of the pipe 10 is an elongated wall surface conveniently in the form of a sheet-metal stampi-ng 14 having a plurality of axially spaced wall stretches 16 extending across lthe interior of the pipe 10 toy form a partitioning wall dividing fthe interior of the pipe 10 into a main gas-flow passage 118 and a plurality of axially spaced resonator volumes'Ztl. The axially extending edges 22 of the wall stretches 16 are Vbent into an arcuate configuration and are rigidly secured to the inner Wall of the pipe d0' in any convenient manner. The wall stretches 16 )are interrupted by axially spaced projections 24 extending out of the plane of said stretches to abut segments of the circumference of the inner Wall of the 3i,ld4,736 Patented Sept. 24, 1963 resonator volumes 20. Preferably, a plurality of stampings 14 are employed and are disposed along only the straight sections of the pipe 14 so as to not interfere with the bending of the pipe 10 into the desired contours.

As shown in FIGS. 2 and 3, lan elongated channeled mern'ber`2f6 is mounted on each of the wall stretches 16 between each adjacent pair of projections Z4 within one of the resonator volumes 20. The axially extending edges 28 of the member 26 are rigidly secured to the wall stretch 16, such as by welding, so that with the open side of the channel presented toward said wall stretchsaid channel and the underlying portion of the wall stretch 16 cooperate to form an elongated resonator volume throat 30. The ends of sai-d throat constitute an opening 32 formed in the Wall stretch 16 in radial and axial alignment `with said channeled member 26 and an open end B4 of said channeled member, the opposite end of said channeled rnember being closed as at 36. Thus, each of the throats 30 operatively interconnects one of the resonator volumes 20 with the main gas-flow passage 18 for silencing the exhaust gases moving through Said passage.

It is well established in the field of resonator design that a longer resonator throat will cause the resonator to attenuate a lower range of sound wave frequencies. Therefore, to tune the resonators so that the volumes 30 will attenuate different ranges of sound wave frequencies, it is merelynecessary to adjust the axial spacing between the openings 32 and the open ends 34 of the channeled members 26. As will be obvious, when the openings 32 are spaced more closely to the open ends 34 to the channeled members 26, Ithe resonator volume 20 in communication therewith will attenuate a higher range of sound wave frequencies than if said openings are spaced farther apart.

A modified form of our invention is illustrated in FIG. 4, and differs from the embodiment show-n in FIG. 3 in that the channeled members 26 are mounted on the face of the Wall stretches '16 to dispose said channeled members in the main gas-ow passage 18' to achieve a more intimate coupling between said main gas-ow passage -18' and the resonator volumes. This difference in the placement of the channeled members 26 is the only difference between the modification shown in lFIG. 4 and the ernbodirnent of our invention shown in FIG. 3, both modifipipe lo and thus form the end walls of the plurality of cations operating in the same manner.

While our invention has been described for use in an exhaust system, it is to be understood, of course, that it can also be used on the intake side of an internal combustion engine for transporting land silencing the gaseous mixture into the engine and for any other operations involving the Itransfer and silencing of gas streams. lt may also be employed in association with other silencing means such as a conventional niuiiler, other types of inline silencers, or the like, in which event it has a relatively short length, Iand does not extend from the engine manifold to the terminal gas discharge point.

We claim as our invention:

l. In =a sound attemrating gas pipe for conveying and attenuating the noise level of a moving gas stream, an elongated pipe, an elongatedl stamping mounted on the inner wall of said pipe and extending thereacross to forni a partitioning wall dividing .the interior of said pipe into a main gas-dow passage and a plurality of axially spaced lresonator volumes, said stamping having a plurality of axially spaced projections labutting circumferential segments of said pipe to form the end Walls of said resonator volumes, and a plurality of elongated channeled members mounted on said stamping and forming therewith a plurality of elongated volume throats, each of -said throats opening into said main gas-flow passage and onev of said volumes to operatively interconnect saidvvolume and the main ,gasow passage for attenuating lthe noise levelV :of the exhaust gases moving through said passage. Y

j'f The invention 4as set forth in claim l in which said stamping is provided with wall ystretches interposed between said' projections with said rnain gas-now passage Vand resonator volumes being disposed on opposite sides of said stretches, and said channeled members are rigidly mounted on said wall stretches. t f Y 3; In a sound attenuating gas pipe for conveying and I attenuatingthe noise level of a moving gas stream, an

elongated pipe, elongated stamping mounted within said pipe and havin-g a plurality of axiallyextendin-g Wall stretches extendingacross ysaid'pipe whereby the portions ofthe pip-e inte-rior on the'opposite sides of said walli stretches 'form Va main Agas-flow passageand a plurality of `axially spacedresonator volumes, a plurality of |axial- V1y spaced projections formed on said stamping integrally ademas n 1y secured Ito the inner wall of -said pipe for holding the stamping in a xed position Iwithin said pipe.V` n

V5. In a sound attenuating gas pipe for conveying and attenuating the noise level of a moving gas stream, an `elongated pipe, an elongated stamping mounted within y said pipeA andhaving 4a plurality of axially extending wall stretches extending across said pipe whereby the portions of the pi-peinterior ori-theV opposite sides of said wall stretches forma main gas-'ow passage and a plurality of laxiallyrspaced resonator volumes,V means interposed between the adjacent ends of adjacent wall stretches and extending between said wall stretches and theinner wall connecting Vits adjacentwall stretches and abutting =cirVV cumferential segments of the inner wall of said pipe to form theend walls of 'said' resonator vo1un1es,andV an elongated channeled member mounted `on each of said wall stretches and acting in combination with the portion of -thewall stretch in alignment therewith to form an elongated resonator volume throat,- said channeled member having an open end and the wallv stretch in alignment therewith having an opening formed therein whereby said rthroat operatively interconnects one `of the volumeswith K the main gas-,now passage 'for attenuating the noise lelvel of the gases passing therethrough.

4. The inventionsas settorth in claim 3 in which said wall stretches have axially extending marginal edges rigidofsaid pipe to form the end walls of said resonator References Cited in the :tile of this patent v VUNITED STATES PATENTS 2,115,103Vr Haas p r Apr. 26, 193s 2,115,113 Y `MacKenzie et al, ---f c"- Apr. 26, 1938 2,274,460 Y, Rauen Feb. V24, 1942 2,297,046 Y Boum-e s sept. 29, 1942 Powers V Sept. 5, 1944V 

1. IN A SOUND ATTENUATING GAS PIPE FOR CONVEYING AND ATTENUATING THE NOISE LEVEL OF A MOVING GAS STREAM, AN ELONGATED PIPE, AN ELONGATED STAMPING MOUNTED ON THE INNER WALL OF SAID PIPE AND EXTENDING THEREACROSS TO FORM A PARTITIONING WALL DIVIDING THE INTERIOR OF SAID PIPE INTO A MAIN GAS-FLOW PASSAGE AND A PLURALITY OF AXIALLY SPACED RESONATOR VOLUMES, SAID STAMPING HAVING A PLURALITY OF 